System for heating and/or cooling a medium

ABSTRACT

The invention relates to a system for heating and/or cooling a medium, comprising an ambient air heat exchanger via which the medium can be heated and/or cooled relative to the ambient air in one or more heat exchanger tubes. The ambient air heat exchanger comprises means for the controlled guidance and/or flow-control of the ambient air along the one or at least one heat exchanger tube, the means for the controlled guidance and/or flow-control of the ambient air being designed to allow a variable or controlled manipulation of the flow speed, flow direction and/or flow intensity of the ambient air.

The invention relates to a system for heating and/or cooling a medium, having an ambient air heat exchanger, via which the medium can be heated and/or cooled in one or more heat exchanger pipes in relation to ambient air.

Systems according to the species for heating and/or cooling a medium, which have an ambient air heat exchanger, are well known from the prior art. They are used in manifold applications for heating and/or cooling a medium to be heated or cooled, for example, a liquefied gas, such as liquefied nitrogen or liquefied oxygen. Since the ambient air is used as the energy supplier in this case, this type of heating and/or cooling a medium represents the most energetically favorable method.

The problem on which the present invention is based and the solution described hereafter are explained hereafter on the basis of the use of a system according to the species for heating and/or cooling a medium in the case of a hydrogen filling station or a hydrogen refueling process. However, it is to be noted that the system according to the invention described hereafter can also be used in manifold further applications, of course.

Hydrogen filling stations typically have a storage container for liquefied hydrogen. The liquid hydrogen withdrawn from this storage container is compressed by means of a so-called cryopump to a delivery or buffer pressure of up to 900 bar. At the outlet of the cryopump, the compressed hydrogen has a temperature between 50 and 60 K. For refueling hydrogen vehicles, the compressed hydrogen must be below a temperature of approximately −40° C., however. The required heating of the compressed hydrogen is performed in a method from the prior art, which is described in German Patent Application 102009019275 (not previously published), for example, by means of a thermoblock, which is cooled and/or heated by means of a refrigerating circuit and/or heating circuit. Alternatively thereto, the thermoblock can also be electrically heated.

The heating of the compressed hydrogen by means of an ambient air heat exchanger has not been considered up to this point, since the media temperature prevailing at the outlet of the ambient air heat exchanger is substantially dependent on the current ambient temperature. This ambient temperature varies within Europe in the course of the year between approximately −30 and 40° C., however. Furthermore, it is disadvantageous that a comparatively good heat transfer occurs at the beginning of the heat exchange process, since the pipelines or the fins attached thereto do not yet have icing. With increasing duration of the heat exchange process, however, stronger and stronger icing of the pipelines or fins occurs, from which a noticeable worsening of the heat transfer can result.

Furthermore, it is disadvantageous that ambient air heat exchangers occupy a comparatively large amount of space, since a minimum spacing between the individual pipelines is to be provided because of the natural convection of the air over the pipelines or fins.

Ambient air heat exchangers according to the species are therefore not used in hydrogen filling stations or hydrogen refueling processes for the above-mentioned reasons, and because the desired media outlet temperature of approximately −40° C. must be maintained with a variation of at most 10° C. The same considerations apply for manifold further applications, in which maintaining a substantially constant media outlet temperature is significant.

The problem of the present invention is to specify a system according to the species for heating and/or cooling a medium, which avoids the disadvantages connected with the above-described methods.

To solve this problem, a system for heating and/or cooling a medium, having an ambient air heat exchanger, via which the medium is heated and/or cooled in one or more heat exchanger pipes in relation to ambient air, is proposed, which is characterized in that the ambient air heat exchanger has means for the controlled guiding and/or incident flow of the ambient air along the or at least one of the heat exchanger pipes, these means being implemented in such a manner that they allow a variable or controllable influence of the flow velocity, direction, and/or intensity of the ambient air.

According to the invention, the intensity of the heat transfer between the ambient air and the medium to be heated and/or cooled can now be influenced, so that the heat transfer—in comparison to a heat transfer which occurs without the aid of the mentioned means for the controlled guiding and/or incident flow of the ambient air—is improved or worsened as a function of the desired heating or cooling. This improvement or worsening of the heat transfer is connected with additional apparatus outlay and therefore additional investment and operating costs, however.

Further advantageous embodiments of the system according to the invention for heating and/or cooling a medium are characterized in that

-   -   the means for the controlled guiding and/or incident flow of the         ambient air are implemented as at least one controllable fan,     -   if the heat exchanger pipe or pipes are arranged in one or more         channels formed by air baffle plates, the means for controlled         guiding and/or incident flow of the ambient air are implemented         as at least one flap 8, which is assigned to the or at least one         of the channels, and which allows partial or complete closing of         the channel,     -   the heat exchanger pipe or pipes are implemented in such a         manner that they withstand pressures up to 1000 bar,     -   the heat exchanger pipe or pipes at least partially consist of a         stainless steel material, and     -   means are provided for the controlled supply of at least one         media stream to the to the ambient air stream guided along the         heat exchanger pipe or pipes.

The system according to the invention for heating and/or cooling a medium and further embodiments thereof are explained in greater detail hereafter on the basis of the exemplary embodiment shown in FIGS. 1 and 2.

FIG. 1 shows a lateral sectional view through the exemplary embodiment, while

FIG. 2 shows a sectional view along line A-A, which is shown by dot-dash line.

As shown on the basis of FIG. 1, the medium to be cooled and/or heated by means of the system according to the invention is supplied via line 1 to the ambient air heat exchanger. This heat exchanger is implemented in the form of heat exchanger pipes 2, which are arranged in a meandering manner. The medium is guided through these pipes through the ambient air heat exchanger, before it is withdrawn via line 3 from the system according to the invention. In practice, a plurality of heat exchanger pipes 2 is typically provided, as shown on the basis of FIG. 2. However, the system according to the invention or the ambient air heat exchanger can fundamentally also have only a single heat exchanger pipe.

In particular if the system according to the invention has a highly compressed medium flowing through it—for example, gaseous hydrogen under a pressure of up to 900 bar—the heat exchanger pipes 2 preferably at least partially consist of a stainless steel material.

In the exemplary embodiment shown in the figures, the meandering area of the heat exchanger pipes 2 is now enclosed by a cylindrical jacket or outer envelope 4. Multiple air baffle plates 5 are arranged therein in such a manner that the ambient air flows substantially parallel to the heat exchanger pipes 2. The provision of the air baffle plates 5 is used in particular for the purpose of avoiding the above-mentioned interfering influences in the case of heat exchanger pipes 2 which are not sufficiently spaced apart, and allowing individual regulation of the air flow along the heat exchanger pipes 2.

As shown on the basis of the arrows illustrating the air flow, the channels formed by the outer envelope 4 and the air baffle plates 5 preferably have the ambient air flowing through them from top to bottom. By means of at least one fan or ventilator V, which is preferably driven by a controllable electric motor M, the strength of the air flow within the outer envelope 4 or the channels formed by the air baffle plates 5 can be varied. Alternatively to the exemplary embodiment shown in FIG. 1, multiple fans, which are preferably assigned to the individual channels, can also be provided. Additionally or alternatively, all or individual channels formed by the air baffle plates 5 can be partially and/or completely closed by means of flaps 8.

In addition, a flow velocity can be set—at least temporarily—by means of the fan or fans V, which allows the frozen material adhering to the heat exchanger pipes 2 or their fans to be detached and entrained by the air flow. In this way, a self-cleaning effect of the heat exchanger pipes 2 or fans can be implemented.

In the embodiment of the system according to the invention shown in FIG. 1, the ambient air guided along the heat exchanger pipes 2 is guided outward in the lower area 6 of the outer envelope or below the outer envelope 4 and withdrawn upward via a ring channel—this is formed by a further cylindrical jacket 7, which encloses the first—mentioned cylindrical jacket 4. This embodiment is used so that the very cold ambient air, which can cause fog, does not flow out unobstructed, since this can result, inter alia, in obstruction of the vision and therefore endangerment of persons standing nearby. The cold air stream is therefore deflected by 180° by means of corresponding guide plates and discharged to the environment at the upper end of the cylindrical jacket 7 at a safe height.

To refine the system according to the invention for heating and/or cooling a medium, it is proposed that means be provided for the controlled supply of at least one media stream to the ambient air stream guided along the heat exchanger pipe or pipes. By means of this design, additional heat or cold—for example, from the waste heat of other refrigerating devices of a hydrogen filling station or a hydrogen refueling process—can be supplied to the supplied ambient air stream and the cooling and/or heating process can thus be supported.

The system according to the invention for heating and/or cooling a medium provides a method, which has a comparatively simple design and is cost-effective, for heating or cooling media, in particular compressed hydrogen, as is provided in hydrogen filling stations after the removal from the reservoir container of the filling station and subsequent compression by means of a cryopump, for example. 

1. A system for heating or cooling a medium, having an ambient air heat exchanger, via which the medium is heated or cooled in relation to ambient air in one or more heat exchanger pipes, characterized in that the ambient air heat exchanger has means for the controlled guiding or incident flow of the ambient air along the or at least one of the heat exchanger pipes, the means for the controlled guiding or incident flow of the ambient air being implemented in such a manner that they allow a variable or controllable influence of the flow velocity, direction, or intensity of the ambient air.
 2. The system according to claim 1, characterized in that the means for controlled guiding and/or incident flow of the ambient air are implemented as at least one controllable fan.
 3. The system according to claim 1, the heat exchanger pipe or pipes being arranged in one or more channels formed by air baffle plates, characterized in that the means for the controlled guiding or incident flow of the ambient air are implemented as at least one flap, assigned to the channel or at least one of the channels, which allows partial or complete closing of the channel.
 4. The system according to claim 1, characterized in that the heat exchanger pipe or pipes are implemented in such a manner that they withstand pressures up to 1000 bar.
 5. The system according to claim 1, characterized in that the heat exchanger pipe or pipes at least partially consist of a stainless steel material.
 6. The system according to claim 1, characterized in that means are provided for the controlled supply of at least one media stream to the ambient air stream guided along the heat exchanger pipe or pipes. 